<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    .box{
      width: 800px;
      margin: 100px auto;
      background-color: #b3d4fc;
      overflow: hidden;
    }
    .daer{
      width: 300px;
      height: 100px;
      background-color: #777777;
      float: left;
    }
    .xiaoer{
      width: 300px;
      height: 200px;
      float: left;
      background-color: #993300;
    }
  </style>
</head>
<body>
<div class="box">
  <div class="daer"></div>
  <div class="xiaoer"></div>
</div>
</body>
</html>
